Għajn Ħadid Tower (Maltese: Torri ta' Għajn Ħadid), originally known as Torre di Salomone[1] and known by locals as Xagħra Tower (Maltese: It-Torri tax-Xagħra),[2] is a ruined watchtower in Selmun, limits of Mellieħa, Malta.

According to a 1743 report in which all coastal towers were inspected due to the fear of a plague, the tower was armed with two bronze cannons, gun wheels and stock, eighteen cannonballs, fifteen rotolos of gunpowder, four muskets and twelve rotolos of musket balls.

A small defensible room pierced by musketry loopholes is located nearby, but it is not known if this predates the tower or if it was built after it.

[3] Għajn Ħadid Tower was severely damaged in an earthquake on 12 October 1856, when its upper floor collapsed.

[4] The commemorative plaque that was originally on the tower is on public display at a garden in Tas-Salib Square in Mellieħa.